On the time-averaging of ultrafine particle number size spectra in vehicular plumes

Abstract

Abstract. Ultrafine vehicular particle (<100 nm) number size distributions presented in the literature are mostly averages of long scan-time (∼30 s or more) spectra mainly due to the non-availability of commercial instruments that can measure particle distributions in the <10 nm to 100 nm range faster than 30 s even though individual researchers have built faster (1-2.5 s) scanning instruments. With the introduction of the Engine Exhaust Particle Sizer (EEPS) in 2004, high time-resolution (1 full 32-channel spectrum per second) particle size distribution data become possible and allow atmospheric researchers to study the characteristics of ultrafine vehicular particles in rapidly and perhaps randomly varying high concentration environments such as roadside, on-road and tunnel. In this study, particle size distributions in these environments were found to vary as rapidly as one second frequently. This poses the question on the generality of using averages of long scan-time spectra for dynamic and/or mechanistic studies in rapidly and perhaps randomly varying high concentration environments. One-second EEPS data taken at roadside, on roads and in tunnels by a mobile platform are time-averaged to yield 5, 10, 30 and 120 s distributions to answer this question.

Seasonal differences of the atmospheric particle size distribution in a metropolitan area in Japan

“…The CPC and SMPS are widely used for measurement of PNCs, but it is rare for an EEPS to be used in the field (e.g., Jacobson et al, 2005;Kittelson et al, 2006;Yao et al, 2006;Minoura et al, 2009). We compared total PNCs and size distributions obtained in a roadside environment with an EEPS with those obtained with CPCs and SMPSs to allow our data to be compared with data from the literature obtained by other instruments.…”

Simultaneous measurements of new particle formation at 1 s time resolution at a street site and a rooftop site

“…FMPSs were used to continuously measure PNSDs with mobility diameters ranging from 5.6 to 560 nm at 1 s time resolution, facilitating the investigation of rapid changes in nanoparticles due to formation and mixing from different sources (Yao et al, 2005(Yao et al, , 2006b. Conductive tubes (TSI 3/8 in., each cut to a length of 2.8 m) were used for sampling at the two sites.…”

Comparison of Vehicle Exhaust Particle Size Distributions Measured by SMPS and EEPS During Steady-State Conditions

“…Early developments by Mirme (1994) at Tartu University and Biskos et al (2005), led to the commercialized systems available today, such as the EEPS by TSI and the DMS500 by Cambustion. In recent years, both the EEPS and DMS500 have been widely used for emission measurement and characterization (Liu et al 2005;Rubino et al 2005;Yao et al 2006;Zervas and Dorlhene, 2006;Zheng et al 2012). The two instruments have multiple electrometers downstream of a corona charger to measure size distributions.…”